Broadband PXI local oscillator modules with low phase noise and fast switching speed

This paper presents two local oscillator modules developed for PXI instrumentation. The modules are based on a novel, patented PLL design that combines fast switching speed, low phase noise, and low spurious characteristics. The modules cover 3-10 and 2-20 GHz frequency ranges respectively. The step size is 0.1 Hz for both modules. The measured phase noise at 10 kHz offset is about -121 dBc/Hz at 10 GHz and -115 dBc/Hz at 20 GHz respectively. The switching time is less than 500 microseconds to be within °50 kHz from the final frequency for any frequency step within the entire operating range. Spurs do not exceed the -70 dBc level. Both developed modules occupy two standard 3-U PXI slots and can be used in a variety of synthetic instruments based on the PXI platform.